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Smoke Detector

Smoke Detector


Across the most of the world’s regulations now require smoke detectors to be installed in homes, schools, public and commercial buildings. In addition to sounding an audible alarm when a fire breaks out, smoke detectors must also communicate an alarm notification to a remote control location, such as the local fire station. To detect smoke an LED inside the smoke sensor illuminates and measures the current corresponding to the amount of light output by a light receiving sensor. The current is converted to a voltage by an op-amp, and the voltage is read using an A/D converter. The LED inside the sensor illuminates at regular intervals controlled by a timer in order to reduce the power consumption by sampling the smoke volume intermittently.

Renesas’ RL78/I1D and RL78/G12, G13, G14 integrate on-chip the peripheral functions necessary for use in smoke detector design, making it possible to reduce the overall product size. Low-voltage operation contributes to extended battery life, which is essential for detectors that must operate over extended periods of time.

System Block Diagram

Recommended Products

BlockSemiconductor deviceRecommended productsFeatures, etc.
Main controllerMCURL78/I1DOperational amplifiers, 12-bit A/D converter and window comparators, very low power operation
RL78/G12, G13, G1432 MHz, 16-bit general purpose, True low power
78K0/Kx2-L 20-pin, low power consumption
H8/38602R Group 32-pin, low power consumption
EEPROMR1EX24xxx SeriesI 2 C bus interface *1
R1EX25xxx SeriesSPI bus interface *2
Op-amp.HA1630xxx SeriesCMOS low power consumption, small package, low voltage operation
μPC358GRBi-polar single power, low power consumption, small pakage
SensorAnalog front endSmart Analog IC300Low voltage configurable amplifier
Configurable amplifier: 3 channels
Operating voltage: 2.2 to 3.6 V (low-voltage product)
Smart Analog IC500Configurable amplifier
Configurable amplifier: 3 channels
Operating voltage: 3.0 to 5.5 V
MCU peripheralReset ICRNA519xx SeriesVariable detection voltage

*1 I 2 C: Inter-Integrated Circuit
*2 SPI: Serial Peripheral Interface

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